Kumar Ravi, Srivastav Saurabh Kumar, Roy Ujjal, Park Jinhong, Spånslätt Christian, Watanabe K, Taniguchi T, Gefen Yuval, Mirlin Alexander D, Das Anindya
Department of Physics, Indian Institute of Science, Bangalore, 560012, India.
Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021, Karlsruhe, Germany.
Nat Commun. 2024 Jun 12;15(1):4998. doi: 10.1038/s41467-024-49446-z.
Collective spin-wave excitations, magnons, are promising quasi-particles for next-generation spintronics devices, including platforms for information transfer. In a quantum Hall ferromagnets, detection of these charge-neutral excitations relies on the conversion of magnons into electrical signals in the form of excess electrons and holes, but if the excess electron and holes are equal, detecting an electrical signal is challenging. In this work, we overcome this shortcoming by measuring the electrical noise generated by magnons. We use the symmetry-broken quantum Hall ferromagnet of the zeroth Landau level in graphene to launch magnons. Absorption of these magnons creates excess noise above the Zeeman energy and remains finite even when the average electrical signal is zero. Moreover, we formulate a theoretical model in which the noise is produced by equilibration between edge channels and propagating magnons. Our model also allows us to pinpoint the regime of ballistic magnon transport in our device.
集体自旋波激发，即磁振子，对于包括信息传输平台在内的下一代自旋电子器件而言，是很有前景的准粒子。在量子霍尔铁磁体中，检测这些电荷中性激发依赖于磁振子以过量电子和空穴的形式转化为电信号，但如果过量电子和空穴相等，检测电信号就具有挑战性。在这项工作中，我们通过测量磁振子产生的电噪声克服了这一缺点。我们利用石墨烯中零朗道能级的对称性破缺量子霍尔铁磁体来激发磁振子。这些磁振子的吸收在塞曼能量之上产生过量噪声，即使平均电信号为零时该噪声仍保持有限。此外，我们建立了一个理论模型，其中噪声是由边缘通道和传播的磁振子之间的平衡产生的。我们的模型还使我们能够确定我们器件中弹道磁振子输运的区域。
